JP5720429B2 - Radiation imaging equipment - Google Patents

Description

  The present invention relates to a radiographic image capturing apparatus, and more particularly, to a radiographic image capturing apparatus in which a radiographic image capturing apparatus detects radiation irradiation by itself and performs radiographic image capturing.

  A so-called direct-type radiographic imaging device that generates electric charges by a detection element in accordance with the dose of irradiated radiation such as X-rays and converts it into an electrical signal, or other radiation such as visible light with a scintillator A so-called indirect radiographic imaging device that converts an electromagnetic wave having a wavelength and then generates a charge in a photoelectric conversion element such as a photodiode according to the energy of the converted electromagnetic wave and converts it to an electrical signal (ie, image data). Have been developed. In the present invention, the detection element in the direct type radiographic imaging apparatus and the photoelectric conversion element in the indirect type radiographic imaging apparatus are collectively referred to as a radiation detection element.

  This type of radiographic imaging apparatus is known as an FPD (Flat Panel Detector), and conventionally formed integrally with a support base (or a bucky apparatus) (see, for example, Patent Document 1). A portable radiographic image capturing apparatus in which an element or the like is stored in a housing and made portable is developed and put into practical use (see, for example, Patent Documents 2 and 3).

  In such a radiographic imaging apparatus, for example, as shown in FIG. 6 and the like, which will be described later, normally, a plurality of radiation detection elements 7 are arranged in a two-dimensional form (matrix) on the detection unit P, and each radiation detection element 7 is connected to switch means formed by thin film transistors (hereinafter referred to as TFTs) 8. Then, an ON voltage or an OFF voltage is applied to each scanning line 5 from the gate driver 15b of the scanning driving unit 15, and each TFT 8 is turned on / off, and charge accumulation in each radiation detection element 7 is performed. Release of charges from each radiation detection element 7 to each signal line 6 is performed.

  By the way, a radiographic image is performed by irradiating a radiation image capturing apparatus from a radiation source of a radiation generating apparatus through a subject. For example, if the manufacturer of the radiation image capturing apparatus and the radiation generating apparatus is the same, it can be configured to perform imaging while exchanging signals and information between the radiation image capturing apparatus and the radiation generating apparatus. .

  However, when the manufacturers of the radiographic imaging apparatus and the radiation generation apparatus are different, it may not be possible to accurately exchange signals and the like as described above. In such a case, it is necessary to detect that the radiation image capturing apparatus itself has irradiated the radiation.

  Therefore, in recent years, various radiographic imaging apparatuses configured to detect themselves that radiation has been emitted have been developed without using such an interface between the radiographic imaging apparatus and the radiation generation apparatus. .

  For example, in Patent Document 4 and Patent Document 5, when radiation is started on the radiation imaging apparatus and a charge is generated in each radiation detection element 7, each radiation detection element 7 is connected to each radiation detection element 7. The current flowing through the bias line 9 is provided by providing a current detection means on the bias line 9 by utilizing the fact that electric charge flows out to the bias line 9 (see FIG. 6 and the like described later) and the current flowing through the bias line 9 increases. It has been proposed to detect the current value and to detect the start of radiation irradiation based on the current value.

  However, as a result of research conducted by the present inventors, the above-described method is based on the fact that the bias line 9 is connected to the electrode of each radiation detection element 7, so that noise generated by the current detection means is detected via each bias line 9. It has been found that there is a problem that is not always easy to solve, such as being superimposed on the image data D transmitted to the element 7 and read out from the radiation detection element 7 as noise.

  And, as a result of various studies on different methods for detecting that the radiation imaging apparatus itself has irradiated the radiation, the present inventors have accurately detected that the radiation imaging apparatus itself has been irradiated. I was able to find some techniques that could be done.

  Incidentally, as will be described later, in the new radiation irradiation detection method found by the present inventors, an off voltage is applied to each scanning line 5 from the scanning drive means 15 before radiographic imaging, and each TFT 8 is turned on. In the off state, the readout circuit 17 performs a readout operation, and the leak data dleak is read out to convert the charge q (see FIG. 10 described later) leaked from the radiation detection element 7 through the TFT 8 into the leak data dleak. Configured to do.

  When the radiation image capturing apparatus is irradiated with radiation, the value of the leak data dleak to be read increases. Therefore, using this, it is configured to detect the start of radiation irradiation on the radiation image capturing apparatus based on the value of the read leak data dleak. In this case, dark charges are accumulated in each radiation detection element 7 if each TFT 8 is kept in an off state. Therefore, as will be described later, the leak data dleak read process and the radiation detection element 7 The reset process is alternately performed.

  Further, in another new radiation irradiation detection method found by the present inventors, an on-voltage is sequentially applied from the scanning drive unit 15 to each of the lines L1 to Lx of the scanning line 5 before radiographic imaging. The image data d is read out. In the following description, the image data for irradiation start detection read out for detection of the start of radiation irradiation before the radiographic image imaging is referred to as image data d, in distinction from the image data D as the main image performed immediately after imaging. .

  Also in this case, the radiation image capturing device is used based on the value of the read image data d by using the increase in the value of the read image data d when the radiation image capturing device is irradiated with radiation. It is configured to detect that irradiation of radiation has started.

  And if comprised as mentioned above, even when an interface cannot be constructed | assembled between a radiographic imaging apparatus and a radiation generator, based on the value of the read leak data dleak or image data d, a radiographic image It has been found that it is possible to accurately detect that radiation has been emitted by the imaging apparatus itself.

  In the radiographic image capturing apparatus, when it is detected that radiation irradiation to the radiographic image capturing apparatus is started as described above, an off voltage is applied from the scanning drive unit 15 to each scanning line 5 and each TFT 8 is turned off. Then, the state shifts to a charge accumulation state in which charges generated by radiation irradiation are accumulated in each radiation detection element 7. After that, the on-voltage is sequentially applied from the scanning drive unit 15 to each scanning line 5, and the reading process of the image data D as the main image from each radiation detection element 7 is performed.

  At that time, in the charge accumulation state in which each TFT 8 is turned off, so-called dark charges, which are always generated due to thermal excitation by the heat (temperature) of the radiation detection element 7 itself, are accumulated in each radiation detection element 7. It becomes a state. The offset due to the dark charge is superimposed on the read image data D.

Therefore, in many cases, the reading process of the offset data O that reads the offset due to the dark charge as the offset data O is performed after the reading process of the image data D as the main image. In the image processing after by calculating the true image data D ^* subtracted from the image data D read out offset data O read, offset by the true image data D ^*, dark charge It is possible to obtain data that is derived only from charges generated by radiation irradiation.

JP-A-9-73144 JP 2006-058124 A JP-A-6-342099 US Pat. No. 7,211,803 JP 2009-219538 A

  By the way, when the offset data O is read out, the offset data O is appropriately subtracted from the offset due to dark charges or the like superimposed on the image data D as the main image in the subtraction process. Various conditions are set so that the values are canceled out.

  That is, for example, after the image data D as the main image is read, the unread portion of the image data D remains in each radiation detection element 7. Therefore, for example, after the reading process of the image data D, the reset process of each radiation detection element 7 is repeatedly performed to remove the unread portion, and then the reading process of the offset data O is performed.

  However, when the above-described detection method of the start of radiation irradiation found by the present inventors is adopted, as described above, in the method of reading the offset data O, which has been conventionally performed, the main image is used. It has been found that the offset due to dark charges or the like superimposed on the image data D and the offset data O may not be offset appropriately.

  This will be specifically described below. Note that, originally, radiography is performed by irradiating the radiographic imaging apparatus with a subject interposed between the radiation source and the radiographic imaging apparatus, but here, in order to explain the above phenomenon in an easy-to-understand manner, Let us consider a state in which radiation is uniformly applied to each radiation detection element 7 of the radiographic imaging apparatus in a state where no subject is present.

  That is, in a state in which no radiation is applied to the radiation image capturing apparatus, for example, as shown in FIG. 27, an on-voltage is sequentially applied to each line L1 to Lx of the scanning line 5 from the gate driver 15b of the scanning driving means 15, Image data d for detecting the start of irradiation is read from the detection element 7. Then, it is assumed that the radiation irradiation start is detected based on the image data d read when the radiation imaging apparatus is uniformly irradiated with radiation and the on-voltage is applied to the line Ln of the scanning line 5. .

  In this case, at that time, the application of the on voltage from the gate driver 15b to each scanning line 5 is stopped, and the off voltage is applied to each scanning line 5 to shift to the charge accumulation state. In this charge accumulation state, charges generated in each radiation detection element 7 due to radiation irradiation are accumulated in each radiation detection element 7.

  Then, after this charge accumulation state is maintained for a predetermined time, for example, the application of the on-voltage is resumed from the line Ln + 1 of the scanning line 5, and the on-voltage is sequentially applied to the lines Ln + 1 to Lx and L1 to Ln of the scanning line 5. The image data D as a main image is read out from each radiation detection element 7 connected to each scanning line 5 by applying the data.

  Subsequently, in order to remove the unread portion remaining in each radiation detection element 7, each radiation detection element 7 is applied by sequentially applying ON voltages to the lines Ln + 1 to Lx and L1 to Ln of the scanning line 5. After repeatedly performing the reset process, the on-voltage is sequentially applied to the lines Ln + 1 to Lx and L1 to Ln of the scanning line 5 to perform the reading process of the image data d for irradiation start detection. Instead of the reading process of the image data d for irradiation start detection, a reset process for each radiation detection element 7 corresponding thereto may be performed.

  Thereafter, the radiation imaging apparatus is left with the off voltage applied to each of the lines L1 to Lx of the scanning line 5 for the same time as the charge accumulation state (in this case, no radiation is irradiated), and the scanning line is left. The application of the on-voltage is restarted from the line Ln + 1 of 5 and the on-voltage is sequentially applied to the lines Ln + 1 to Lx and L1 to Ln of the scanning line 5 to detect each radiation connected to each scanning line 5. The offset data O is read from each element 7.

If the experiment as described above is performed, the offset due to the dark charge or the like superimposed on the image data D read out as the main image and the offset data O read out after that are obtained for each radiation detection element 7. Should have the same value. Therefore, by subtracting the offset data O from the image data D to calculate the true image data D ^* , the offset amount superimposed on the image data D and the offset data O should be offset. Therefore, the true image data D ^* should have the same value for each radiation detection element 7.

However, actually, as shown in FIG. 28, between the line Ln of the scanning line 5 where the start of radiation irradiation is detected and the line Ln + 1 of the scanning line 5 where reading of the image data D and the like is started, It has been found that a so-called step may occur in the true image data D ^* . Note that in FIG. 28, the magnitude of the true image data D ^* is expressed in light and dark, and in order to make the figure easy to see, the difference in size (light and dark) is expressed with greater emphasis than in actuality.

The step in the true image data D ^* also appears when shooting is performed through the subject. When a step is generated in the true image data D ^* as described above, for example, when a radiographic image captured by a radiographic image capturing apparatus is used for medical diagnosis, the true image data D ^* corresponds to the step. A streak appears in the image portion, making it difficult to see the radiation image. In addition, when the streak-shaped image portion and the lesioned part of the patient overlap on the radiographic image, the lesioned part may be difficult to see and the lesioned part may be overlooked.

The present invention has been made in view of the above-described problems, and can accurately detect that radiation has been emitted by the radiographic imaging apparatus itself, and can further provide a step difference in true image data D ^* . An object of the present invention is to provide a radiographic image capturing apparatus capable of accurately preventing the occurrence of the above-described problem.

In order to solve the above-described problem, the radiographic imaging device of the present invention includes:
A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other, and a plurality of radiation detection elements arranged in a two-dimensional manner in each small region partitioned by the plurality of scanning lines and the plurality of signal lines A detection unit comprising:
Scan driving means for applying an on voltage or an off voltage to each of the scanning lines;
Switch means connected to each of the scanning lines and causing the signal lines to discharge charges accumulated in the radiation detection element when an on-voltage is applied;
A readout circuit that converts the electric charge emitted from the radiation detection element into image data and reads the image data;
Control means for controlling at least the scanning drive means and the readout circuit to perform readout processing of the image data from the radiation detection element;
With
The control means includes
The charge leaked from each radiation detection element via each switch means in a state where an off voltage is applied to each scan line from the scan driving means to turn off each switch means before radiographic image capturing. Alternately performing leak data read processing for converting the data into leak data and reset processing of the radiation detection elements performed by sequentially applying an ON voltage to the scan lines from the scan driving unit,
When it is detected that radiation irradiation has started when the read leak data exceeds a threshold value, an off voltage is applied to each scanning line from the scanning drive means to generate charges generated by radiation irradiation. After shifting to a charge accumulation state to be accumulated in the radiation detection element, the image data is read from each radiation detection element, and
After the image data read processing, the leak data read processing and the radiation detection element of each of the radiation detection elements are performed in the same cycle as the leak data read processing and the reset processing of each radiation detection element performed before the start of radiation irradiation detection. The reset process is alternately performed, and after applying an off voltage to the scan lines from the scan driving unit for the same time as the charge accumulation state, the radiation detection elements are applied at the same cycle as the image data read process. The offset data is read out.

Moreover, the radiographic imaging device of the present invention is
A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other, and a plurality of radiation detection elements arranged in a two-dimensional manner in each small region partitioned by the plurality of scanning lines and the plurality of signal lines A detection unit comprising:
Scan driving means for applying an on voltage or an off voltage to each of the scanning lines;
Switch means connected to each of the scanning lines and causing the signal lines to discharge charges accumulated in the radiation detection element when an on-voltage is applied;
A readout circuit that converts the electric charge emitted from the radiation detection element into image data and reads the image data;
Control means for controlling at least the scanning drive means and the readout circuit to perform readout processing of the image data from the radiation detection element;
With
The control means includes
Prior to radiographic image capturing, an on voltage is sequentially applied to each scanning line from the scanning driving means to perform a reading process of the image data for detection of irradiation start,
When it is detected that radiation irradiation has started when the read image data exceeds a threshold value, an off voltage is applied to each scanning line from the scanning drive means to generate charges generated by radiation irradiation. After shifting to a charge accumulation state to be accumulated in the radiation detection element, the image data as a main image from each radiation detection element is read out, and
After the reading process of the image data as the main image, the reading process of the image data for detecting the start of irradiation is performed at the same cycle as the reading process of the image data for detecting the start of irradiation performed before detecting the start of irradiation of radiation. In addition, after applying an off voltage to the scanning lines from the scanning driving means for the same time as the charge accumulation state, the offset data from the radiation detection elements is in the same cycle as the read processing of the image data as the main image. It is characterized in that the reading process is performed.

  According to the radiographic imaging apparatus of the system of the present invention, before the radiographic imaging, the leak data dleak and the image data d for detecting the start of irradiation are read out, and based on this, the start of radiation irradiation is detected. Therefore, it is possible to accurately detect that the radiation image capturing apparatus 1 itself has irradiated the radiation.

  Further, the offset due to the dark charge included in the image data D as the main image, the offset due to the total value of the charge q leaked from each radiation detection element 7, and those offset included in the offset data O are obtained. The same value can be set for each radiation detection element 7.

  Therefore, by subtracting the offset data O from the image data D as the main image, the offset due to the dark charge and the offset due to the total value of the leaked charge q can be canceled out accurately, respectively. The offset amount superimposed on the image data D and the offset data O are accurately offset.

Therefore, by subtracting the offset data O from the main image data D, it is possible to accurately prevent a step (see FIG. 28) from occurring in the true image data D ^* calculated for each radiation detection element 7. Become. And when using the radiographic image image | photographed with the radiographic imaging apparatus 1 for the medical diagnosis etc., a streak appears in a radiographic image, or a streak and a lesion part of a patient overlap on a radiographic image, and a lesion part It is possible to accurately prevent problems such as oversight.

It is a perspective view which shows the external appearance of the radiographic imaging apparatus which concerns on this embodiment. It is sectional drawing which follows the XX line in FIG. It is a top view which shows the structure of the board | substrate of a radiographic imaging apparatus. It is an enlarged view which shows the structure of the radiation detection element, TFT, etc. which were formed in the small area | region on the board | substrate of FIG. It is a side view explaining the board | substrate with which a flexible circuit board, a PCB board | substrate, etc. were attached. It is a block diagram showing the equivalent circuit of a radiographic imaging apparatus. It is a block diagram showing the equivalent circuit about 1 pixel which comprises a detection part. It is a timing chart showing the ON / OFF timing of the charge reset switch and TFT in the reset processing of each radiation detection element. 6 is a timing chart showing charge reset switches, pulse signals, and TFT on / off timings in image data read processing. It is a figure explaining that each electric charge which leaked from each radiation detection element via TFT is read as leak data. 6 is a timing chart showing on / off timings of charge reset switches and TFTs in a leak data read process. 6 is a timing chart showing charge reset switches, pulse signals, and on / off timings of TFTs in a case where leak data reading processing and radiation detection element reset processing are alternately performed before radiographic imaging. 6 is a timing chart for explaining the timing of applying an on-voltage to each scanning line in the detection method 1; It is the graph which plotted the leak data read out in time series. It is a timing chart explaining the timing etc. which apply an ON voltage to each scanning line in the reset process of each normal radiation detection element. 10 is a timing chart showing the timing of sequentially applying an on-voltage to each scanning line when image data reading processing for detecting irradiation start is repeatedly performed in the detection method 2; 10 is a timing chart showing a charge reset switch, a pulse signal, TFT on / off timing, and an on time ΔT in a reading process of image data for irradiation start detection. 6 is a timing chart for explaining the timing of applying an ON voltage to each scanning line in the detection method 2; FIG. 14 is a timing chart for explaining timings for applying an ON voltage to each scanning line when the offset data reading process is performed by repeating the processing sequence shown in FIG. 13. FIG. (A) It is a graph showing the transition of the potential of the signal line, etc. when only reset processing of each radiation detection element 7 is performed, and (B) when leak data reading processing and reset processing are alternately performed. It is a figure showing the relationship between the transition of the potential of the signal line and the effective accumulation time at the time of (A) main image data read processing and (B) offset data read processing. (A) A graph in which offsets due to dark charges superimposed on main image data and (B) offset data are plotted for each scanning line. 6 is a graph showing a state in which an offset due to dark charge superimposed on main image data and offset data are not canceled and a step is generated. It is the graph which plotted the leak total value read during read-out operation of this image data in time series. It is the graph which plotted the leak total value read after the reset process of each normal radiation detection element in time series. It is the graph which plotted the difference value which subtracted the leak total value contained in offset data from the leak total value contained in this image data for every scanning line. It is a figure explaining the state etc. which read the image data for irradiation start detection from each radiation detection element by sequentially applying ON voltage to each scanning line. It is a figure showing the level | step difference which arises in true image data.

  Embodiments of a radiographic image capturing apparatus according to the present invention will be described below with reference to the drawings.

  In the following description, a so-called indirect radiation image capturing apparatus that includes a scintillator or the like and converts an emitted radiation into an electromagnetic wave having another wavelength such as visible light to obtain an electrical signal will be described. The present invention can also be applied to a so-called direct type radiographic imaging apparatus that directly detects radiation with a radiation detection element without using a scintillator or the like.

  Further, the present invention is not limited to the so-called portable radiographic image capturing apparatus described in the present embodiment, but also, for example, a fixed (also referred to as a dedicated machine type) radiographic image that is formed integrally with a support stand or the like. The present invention can be applied to an apparatus.

  FIG. 1 is a perspective view showing an external appearance of the radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line XX of FIG. In the present embodiment, as shown in FIGS. 1 and 2, the radiographic image capturing apparatus 1 includes a sensor panel SP configured by a scintillator 3, a substrate 4, and the like in a housing 2.

  In the present embodiment, a hollow rectangular tube-shaped housing body 2A having a radiation incident surface R in the housing 2 is formed of a material such as a carbon plate or plastic that transmits radiation, and the housing body 2A. The housing 2 is formed by closing the opening portions on both sides with lid members 2B and 2C.

  Further, the lid member 2B on one side of the housing 2 has a power switch 37, a changeover switch 38, a connector 39, an indicator 40 composed of an LED or the like for displaying a battery state, an operating state of the radiographic imaging apparatus 1, and the like. Is arranged.

  Although not shown, in this embodiment, the connector 39 can be connected to a connector provided at the end of the cable. By connecting with a cable, for example, signals and the like can be transmitted to and received from a console (not shown), and image data D and the like can be transmitted to the console.

  Although not shown, for example, the antenna device 41 (see FIG. 6 described later) is provided, for example, in the lid member 2C on the opposite side of the housing 2 so as to be embedded in the lid member 2C. Then, the antenna device 41 functions as a communication means when transmitting and receiving a radio signal such as a signal between the radiographic imaging device 1 and the console.

  As shown in FIG. 2, a substrate 4 is disposed inside the housing 2 via a lead thin plate (not shown) on the upper surface side of the base 31, and an electronic component is disposed on the lower surface side of the base 31. A PCB substrate 33, a battery 24, and the like on which 32 and the like are disposed are attached. Further, a glass substrate 34 for protecting the substrate 4 and the radiation incident surface R of the scintillator 3 is disposed. Moreover, in this embodiment, the buffer material 35 for preventing that they collide between the base 31, the board | substrate 4, etc., and the side surface of the housing | casing 2 is provided.

  The scintillator 3 is provided at a position on the substrate 4 that faces a detection unit P described later. In the present embodiment, the scintillator 3 is, for example, a phosphor whose main component is converted into an electromagnetic wave having a wavelength of 300 to 800 nm, that is, an electromagnetic wave centered on visible light and output when receiving radiation. .

  In the present embodiment, the substrate 4 is formed of a glass substrate. As shown in FIG. 3, a plurality of scanning lines 5 and a plurality of signal lines are provided on a surface 4 a of the substrate 4 facing the scintillator 3. 6 are arranged so as to cross each other. In each small region r defined by the plurality of scanning lines 5 and the plurality of signal lines 6 on the surface 4 a of the substrate 4, radiation detection elements 7 are respectively provided. In this way, the entire small region r provided with a plurality of radiation detection elements 7 arranged in a two-dimensional manner in each small region r partitioned by the scanning line 5 and the signal line 6, that is, shown by a one-dot chain line in FIG. The area to be detected is the detection unit P.

  In the present embodiment, a photodiode is used as the radiation detection element 7, but other than this, for example, a phototransistor or the like can also be used. As shown in FIG. 4 which is an enlarged view of FIG. 3, each radiation detection element 7 is connected to a source electrode 8s of a TFT 8 which is a switch means. The drain electrode 8 d of the TFT 8 is connected to the signal line 6.

  When the radiation detection element 7 receives radiation from the radiation incident surface R of the housing 2 of the radiographic imaging apparatus 1 and is irradiated with electromagnetic waves such as visible light converted from the radiation by the scintillator 3, the radiation detection element 7 has electron positive inside. Generate hole pairs. In this way, the radiation detecting element 7 converts the irradiated radiation (electromagnetic wave converted from the radiation by the scintillator 3 in this embodiment) into electric charge.

  The TFT 8 is turned on when a turn-on voltage is applied to the gate electrode 8g via the scanning line 5 from the scanning driving means 15 described later, and is accumulated in the radiation detection element 7 via the source electrode 8s and the drain electrode 8d. The charged electric charge is discharged to the signal line 6. The TFT 8 is turned off when an off voltage is applied to the gate electrode 8g via the connected scanning line 5, and the emission of the charge from the radiation detecting element 7 to the signal line 6 is stopped, and the radiation detecting element The electric charge is accumulated in 7.

  In the present embodiment, as shown in FIG. 4, one bias line 9 is connected to a plurality of radiation detecting elements 7 arranged in rows, and as shown in FIG. Each is arranged in parallel to the signal line 6. Further, each bias line 9 is bound to the connection 10 at a position outside the detection portion P of the substrate 4.

  In the present embodiment, as shown in FIG. 3, each scanning line 5, each signal line 6, and connection 10 of the bias line 9 are input / output terminals (also referred to as pads) provided near the edge of the substrate 4. ) 11.

  As shown in FIG. 5, each input / output terminal 11 has a flexible circuit board (Chip On Film or the like) on which a chip such as a gate IC 15c constituting a gate driver 15b of a scanning drive means 15 described later is incorporated on a film. 12) are connected via an anisotropic conductive adhesive material 13 such as an anisotropic conductive adhesive film (Anisotropic Conductive Film) or an anisotropic conductive paste (Anisotropic Conductive Paste).

  The flexible circuit board 12 is routed to the back surface 4b side of the substrate 4 and connected to the PCB substrate 33 described above on the back surface 4b side. In this way, the sensor panel SP of the radiation image capturing apparatus 1 is formed. In FIG. 5, illustration of the electronic component 32 and the like is omitted.

  Here, the circuit configuration of the radiation image capturing apparatus 1 will be described. FIG. 6 is a block diagram showing an equivalent circuit of the radiation image capturing apparatus 1 according to the present embodiment, and FIG. 7 is a block diagram showing an equivalent circuit for one pixel constituting the detection unit P.

  As described above, each radiation detection element 7 of the detection unit P of the substrate 4 has the bias line 9 connected to the second electrode 7b, and each bias line 9 is bound to the connection 10 to the bias power source 14. It is connected. The bias power supply 14 applies a bias voltage to the second electrode 7 b of each radiation detection element 7 via the connection 10 and each bias line 9. The bias power supply 14 is connected to a control means 22 described later, and the control means 22 controls the bias voltage applied to each radiation detection element 7 from the bias power supply 14.

  As shown in FIGS. 6 and 7, in the present embodiment, the bias power supply 14 supplies the second electrode 7 b of the radiation detection element 7 to the first electrode 7 a side of the radiation detection element 7 as a bias voltage via the bias line 9. A voltage equal to or lower than the voltage applied to (i.e., a so-called reverse bias voltage) is applied.

  The scanning drive means 15 includes a power supply circuit 15a for supplying an on voltage and an off voltage to the gate driver 15b via the wiring 15d, and a voltage applied to each line L1 to Lx of the scanning line 5 between the on voltage and the off voltage. A gate driver 15b that switches between the on state and the off state of each TFT 8 is provided.

  As shown in FIGS. 6 and 7, each signal line 6 is connected to each readout circuit 17 incorporated in the readout IC 16. The readout circuit 17 includes an amplification circuit 18 and a correlated double sampling circuit 19. An analog multiplexer 21 and an A / D converter 20 are further provided in the read IC 16. 6 and 7, the correlated double sampling circuit 19 is represented as CDS. In FIG. 7, the analog multiplexer 21 is omitted.

In the present embodiment, the amplifier circuit 18 is a charge amplifier circuit including an operational amplifier 18a, a capacitor 18b and a charge reset switch 18c connected in parallel to the operational amplifier 18a, and a power supply unit 18d that supplies power to the operational amplifier 18a and the like. It consists of The signal line 6 is connected to the inverting input terminal on the input side of the operational amplifier 18 a of the amplifier circuit 18, and the reference potential V ₀ is applied to the non-inverting input terminal on the input side of the amplifier circuit 18. . Note that the reference potential V ₀ is set to an appropriate value, and in this embodiment, for example, 0 [V] is applied.

  The charge reset switch 18 c of the amplifier circuit 18 is connected to the control means 22, and is turned on / off by the control means 22. Further, a switch 18e that opens and closes in conjunction with the charge reset switch 18c is provided between the operational amplifier 18a and the correlated double sampling circuit 19, and the switch 18e is turned on / off by the charge reset switch 18c. It is designed to be turned off / on in conjunction with

  When the radiographic imaging apparatus 1 performs reset processing of each radiation detection element 7 for removing the charge remaining in each radiation detection element 7, the charge reset switch 18c is turned on as shown in FIG. Each TFT 8 is turned on in the state (and the switch 18e is turned off).

  Then, electric charges are discharged from the radiation detecting elements 7 to the signal lines 6 through the TFTs 8, and the electric charges pass through the electric charge reset switch 18c of the amplifier circuit 18 and pass through the operational amplifier 18a from the output terminal side of the operational amplifier 18a. From the non-inverting input terminal, it is grounded or flows out to the power supply unit 18d. In this way, the reset processing of each radiation detection element 7 is performed.

  On the other hand, in the reading process of the image data D as the main image from each radiation detection element 7 or the reading process of the image data d for irradiation start detection described later, as shown in FIG. When the charge reset switch 18c is turned off (and the switch 18e is turned on), the charge is released from the radiation detection elements 7 to the signal lines 6 through the TFTs 8 turned on. Is stored in the capacitor 18 b of the amplifier circuit 18.

  In the amplifier circuit 18, a voltage value corresponding to the amount of charge accumulated in the capacitor 18b is output from the output side of the operational amplifier 18a. The correlated double sampling circuit (CDS) 19 outputs the pulse signal Sp1 (see FIG. 9) from the control means 22 before the electric charge flows out from each radiation detecting element 7, and at that time, the correlated double sampling circuit (CDS) 19 outputs the amplified signal from the amplifier circuit 18. Holds the voltage value Vin.

  Then, after the electric charge flowing out from each radiation detection element 7 is accumulated in the capacitor 18b of the amplifier circuit 18, when the pulse signal Sp2 is transmitted from the control means 22, the voltage value output from the amplifier circuit 18 at that time point. Holds Vfi. Then, a voltage value difference Vfi−Vin is calculated, and the calculated difference Vfi−Vin is output downstream as analog value image data D.

  The image data D of each radiation detection element 7 output from the correlated double sampling circuit 19 is sequentially transmitted to the A / D converter 20 via the analog multiplexer 21, and the digital value is sequentially converted by the A / D converter 20. It is converted into image data D, outputted to the storage means 23 and sequentially stored.

  When one reading process of the image data D is completed, the charge reset switch 18c of the amplifier circuit 18 is turned on (see FIG. 9), and the charge accumulated in the capacitor 18b is discharged, and the same as above. On the other hand, the discharged electric charge passes through the operational amplifier 18a from the output terminal side of the operational amplifier 18a, goes out from the non-inverting input terminal, is grounded, or flows out to the power supply unit 18d.

  The control means 22 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, etc., not shown, connected to a bus, an FPGA (Field Programmable Gate Array), or the like. It is configured. It may be configured by a dedicated control circuit.

  And the control means 22 controls operation | movement etc. of each member of the radiographic imaging apparatus 1. As shown in FIG. 6 and the like, the control means 22 is connected to a storage means 23 composed of SRAM (Static RAM), SDRAM (Synchronous DRAM) or the like.

  In the present embodiment, the antenna unit 41 described above is connected to the control unit 22, and each member such as the detection unit P, the scanning drive unit 15, the readout circuit 17, the storage unit 23, the bias power supply 14, and the like. A battery 24 for supplying electric power is connected. The battery 24 is provided with a connection terminal 25 that is used when the battery 24 is charged by supplying power to the battery 24 from a charging device (not shown).

  As described above, the control unit 22 controls the bias power supply 14 to set or vary the bias voltage applied from the bias power supply 14 to each radiation detection element 7. It is designed to control the operation.

[Configuration for detection of radiation irradiation start]
Next, a basic configuration of detection processing for realizing the new radiation irradiation start detection method found by the present inventors in the radiographic imaging apparatus 1 according to the present embodiment will be described.

  In the present embodiment, an interface is not constructed between the radiographic image capturing apparatus 1 and a radiation generator (not shown), and the radiographic image capturing apparatus 1 itself detects that radiation has been emitted. Hereinafter, a method of detecting the start of radiation irradiation performed by the radiation image capturing apparatus 1 according to the present embodiment will be described.

  Note that the detection method according to the present embodiment is a detection method newly found by the inventors' research, and as described in Patent Document 4 and Patent Document 5 described above, a current is generated in the apparatus. A method of providing a detection unit and detecting the start of radiation irradiation based on an output value from the current detection unit is not employed. As a detection method newly found by the inventors' research, for example, any of the following two detection methods can be adopted.

[Detection method 1]
For example, before the radiation image capturing apparatus 1 is irradiated with radiation in the radiation image capturing, it is possible to repeatedly perform the reading process of the leak data dleak. Here, as shown in FIG. 10, the leak data dleak is a charge q leaked from each radiation detection element 7 via each TFT 8 which is in an OFF state in a state where an OFF voltage is applied to each scanning line 5. This data corresponds to the total value for each signal line 6.

  In the reading process of the leak data dleak, unlike the reading process of the image data D shown in FIG. 9, as shown in FIG. 11, an off voltage is applied to each line L <b> 1 to Lx of the scanning line 5. With the TFT 8 turned off, the control means 22 transmits the pulse signals Sp1 and Sp2 to the correlated double sampling circuit 19 (see CDS in FIG. 6 and FIG. 7) of each readout circuit 17.

  When the pulse signal Sp <b> 1 is transmitted from the control unit 22, the correlated double sampling circuit 19 holds the voltage value Vin output from the amplifier circuit 18 at that time. Then, the charge q leaked from each radiation detection element 7 via each TFT 8 is accumulated in the capacitor 18b of the amplifier circuit 18 to increase the voltage value output from the amplifier circuit 18, and the pulse signal Sp2 is transmitted from the control means 22. Then, the correlated double sampling circuit 19 holds the voltage value Vfi output from the amplifier circuit 18 at that time.

  And the value which the correlated double sampling circuit 19 calculated and output the difference Vfi−Vin of the voltage value becomes the leak data dleak. The leak data dleak is then converted into a digital value by the A / D converter 20 as in the case of the image data D reading process described above.

  However, if only the reading process of the leak data dleak is repeatedly performed, each TFT 8 remains in an off state, and the dark charge generated in each radiation detection element 7 is continuously accumulated in each radiation detection element 7. Become.

  Therefore, in this detection method 1, as shown in FIG. 12, the leakage data dleak is read in a state in which the off voltage is applied to each scanning line 5, and the on voltage is sequentially applied to each line L <b> 1 to Lx of the scanning line 5. It is desirable that the reset processing of each radiation detection element 7 performed by applying is alternately performed. Note that T and τ in FIG. 12 and FIG. 13 described later will be described later.

  Hereinafter, the reset process of each radiation detection element 7 performed alternately with the readout process of the leak data dleak is referred to as “the reset process of each radiation detection element 7 performed alternately with the readout process dleak of the leak data”. On the other hand, as shown in FIG. 15 to be described later, a normal reset process of each radiation detection element 7 which is performed by sequentially applying an ON voltage to each line L1 to Lx of the scanning line 5 without a leak data dleak read process. Is referred to as “ordinary reset processing of each radiation detection element 7” or “reset processing of each radiation detection element 7 without leak data dleak readout processing”. In this embodiment, as described above, the reset processing of each radiation detection element 7 is described separately.

  As described above, when the readout process of the leak data dleak and the reset process of each radiation detection element 7 are alternately performed before radiographic imaging, when radiation irradiation to the radiographic imaging apparatus 1 is started, Each TFT 8 is irradiated with an electromagnetic wave converted from radiation by the scintillator 3 (see FIG. 2). As a result, the inventors have found that the charges q (see FIG. 10) leaking from the radiation detecting elements 7 via the TFTs 8 increase.

  And, for example, as shown in FIG. 13, when the readout process of the leak data dleak and the reset process of each radiation detection element 7 are alternately performed before radiographic imaging, as shown in FIG. The leak data dleak read out at the time when the irradiation of radiation is started becomes much larger than the leak data dleak read out before that time.

  13 and 14, the leak data dleak read in the fourth read process after the on-voltage is applied to the line L4 of the scanning line 5 in FIG. 13 and the reset process is performed is shown in FIG. Corresponds to the leak data dleak at time t1. In FIG. 13, “R” represents a reset process for each radiation detection element 7, and “L” represents a read process for leak data dleak. Note that Tac in FIG. 13 will be described later.

  Therefore, the control means 22 of the radiographic image capturing apparatus 1 is configured to monitor the leak data dleak read out in the read processing of the leak data dleak before radiographic image capture, and the read out leak data dleak is, for example, It can be configured to detect that radiation irradiation has started when a predetermined threshold value threshold_th (see FIG. 14) is exceeded.

  In addition, the normal reset process of each radiation detection element 7 is performed by sequentially applying an ON voltage from the scanning drive unit 15 to each of the lines L1 to Lx of the scanning line 5, as shown in FIG.

  As can be seen by comparing this with FIG. 12, when the detection method 1 is configured to alternately perform the readout process of the leak data dleak and the reset process of each radiation detection element 7 (see FIG. 12), The on-voltage is applied to the next scanning line 5 after the on-voltage is applied to the scanning line 5 by the amount corresponding to the reading process of the leak data dleak, as compared with the reset processing of each radiation detection element 7 (see FIG. 15). There is a feature that the period τ until the application of is long.

  Further, in order to improve the sensitivity of the read leak data dleak, the period τ and the transmission interval T (see FIG. 12) of the pulse signals Sp1 and Sp2 may be set to be long. In such a case, the period τ is longer than the normal reset process of each radiation detection element 7.

  On the other hand, when the control means 22 detects the start of radiation irradiation as described above, it stops applying the on-voltage to each scanning line 5 at that time as shown in FIG. Then, an off voltage is applied from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5, each TFT 8 is turned off, and the charge generated in each radiation detecting element 7 due to radiation irradiation is stored in each radiation detecting element 7. To the charge accumulation state to be accumulated in.

  Then, after a predetermined time has elapsed since the start of radiation irradiation was detected, the control means 22 detects, for example, the start of radiation irradiation in the readout process of the leak data dleak before radiographic image capturing. The scanning line 5 to which the on-voltage is to be applied next to the scanning line 5 (the line L4 of the scanning line 5 in the case of FIG. 13) to which the on-voltage is applied in the immediately preceding reset process (the line of the scanning line 5 in the case of FIG. 13). The application of the ON voltage is started from L5), the ON voltage is sequentially applied to each scanning line 5, and the image data D as the main image is read out.

  Note that, hereinafter, the scanning line 5 to which the on-voltage is applied in the reset process immediately before the start of radiation irradiation is detected in the reading process of the leak data dleak before the radiographic imaging (scanning in the case of FIG. 13). The line L4 of the line 5 is called a detection line, and the scanning line 5 to which the ON voltage is applied when the reading process of the image data D as the main image is started (in the case of FIG. 13, the line L5 of the scanning line 5). ) Is called a read start line.

  Also, instead of setting the readout start line as the line next to the detection line of the scanning line 5 (line L4 of the scanning line 5 in the case of FIG. 13) (line L5 of the scanning line 5 in the case of FIG. 13) as described above. In addition, for example, the first line L1 of the scanning line 5 may be used.

[Detection method 2]
Further, as shown in FIG. 16, instead of the configuration in which the leak data dleak is read before the radiographic image is captured as in the detection method 1 described above, the gate of the scanning drive unit 15 is configured as illustrated in FIG. 16 before the radiographic image is captured. It is also possible to apply a turn-on voltage to the lines L1 to Lx of the scanning line 5 from the driver 15b in order to read out the image data d from each radiation detection element 7.

  In addition, as described above, the image data D for irradiation start detection read out for detection of the start of radiation irradiation before the radiographic image capturing is distinguished below from the image data D as the main image performed immediately after the imaging. Is referred to as image data d. Hereinafter, the image data D as the main image is referred to as main image data D.

  In addition, on / off of the charge reset switch 18c of the amplification circuit 18 of the readout circuit 17 and transmission of the pulse signals Sp1 and Sp2 to the correlated double sampling circuit 19 in the readout process of the image data d are shown in FIG. As described above, the processing is performed in the same manner as in the reading processing of the image data D shown in FIG. Note that ΔT in FIG. 17 and the like will be described later.

  When the image data d is read out before radiographic imaging as described above, as shown in FIG. 18, when radiation irradiation to the radiographic imaging device 1 is started, readout is performed at that time. The image data d (in FIG. 18, the image data d read by applying the on-voltage to the line Ln of the scanning line 5) is the same as before the leak data dleak shown in FIG. The image data d is much larger than the image data d read out.

  Therefore, the control means 22 of the radiographic image capturing apparatus 1 is configured to monitor the image data d read in the read process before radiographic image capturing, and the read image data d is set to a predetermined value set in advance. It can be configured to detect that radiation irradiation has started when the threshold value dth is exceeded.

  In this case, when the control unit 22 detects that the irradiation of radiation has started as described above, the application of the on-voltage to each scanning line 5 is stopped at that time as shown in FIG. Then, an off voltage is applied from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5, each TFT 8 is turned off, and the electric charge generated in each radiation detecting element 7 due to radiation irradiation is applied to each radiation detecting element. 7 is shifted to a charge accumulation state to be accumulated in the inside.

  For example, after a predetermined time has elapsed since the start of radiation irradiation was detected, the control unit 22 is turned on when it is detected that radiation irradiation has started in the reading process of the image data d before the radiographic image capturing. The scanning line 5 to which the ON voltage is to be applied next to the scanning line 5 to which the voltage is applied (in the case of FIG. 18, the line Ln of the scanning line 5, ie, the detection line Ln) (in the case of FIG. 18, the line Ln of the scanning line 5). +1, that is, the application of the on-voltage is started from the reading start line Ln + 1), and the on-voltage is sequentially applied to each scanning line 5 to perform the reading process of the main image data D.

  In the case shown in FIG. 18 as well, the readout start line is the line following the detection line of scanning line 5 (line Ln of scanning line 5 in the case of FIG. 18) as described above (scanning in the case of FIG. 18). Instead of the line Ln + 1) of the line 5, for example, the first line L1 of the scanning line 5 may be used. Further, ΔT and the like in FIG. 18 will be described below.

  In the case of this detection method 2, the on / off control of the charge reset switch 18c (see FIG. 17), the transmission interval of the pulse signals Sp1 and Sp2, and each line of the scanning line 5 in the reading process of the image data d for detecting irradiation start The application time (hereinafter referred to as “on time”) ΔT of the on-voltage for L1 to Lx can be configured to be performed under the same conditions as in the case of the reading process of the main image data D.

  Further, in order to improve the sensitivity of the read image data d, the above-described on-time ΔT shown in FIG. 18 and the period from when the on-voltage is applied to a certain scanning line 5 to when the on-voltage is applied to the next scanning line 5 In some cases, the period τ is set to be long. In such a case, the on-time ΔT and the period τ are longer than in the case of the reading process of the main image data D.

[About offset data read processing]
Next, the offset data O reading process performed after the reading process of the main image data D in the radiographic image capturing apparatus 1 according to the present embodiment will be described.

  As described above, when the control unit 22 detects the start of radiation irradiation as described above (see FIG. 13 and FIG. 18 and the like), it applies an off voltage to the lines L1 to Lx of the scanning line 5 from the gate driver 15b. To shift to the charge accumulation state. Thereafter, an on-voltage is sequentially applied to each scanning line 5 to perform a reading process of the main image data D.

  When the control unit 22 performs the reading process of the main image data D, the control unit 22 continues to perform the reading process of the offset data O.

  In the present embodiment, the offset data O reading process is performed by repeating the same processing sequence as the processing sequence before the start of radiation irradiation detection (see FIGS. 13 and 18). However, in this case, the radiation image capturing apparatus 1 is not irradiated with radiation.

  That is, in the offset data O reading process, after the reading process of the main image data D, for example, as shown in FIG. In the same cycle as the process and the reset process of each radiation detection element 7 (see FIG. 13), the readout process of the leak data dleak (see “L” in FIG. 19) and the reset process of each radiation detection element 7 (in FIG. 19) Are alternately performed at least once for each scan line.

  Then, after applying the off-voltage to each scanning line 5 from the scanning drive unit 15 for the same time as the charge accumulation state before the start of radiation irradiation detection (see FIG. 13) (see “charge accumulation state” in FIG. 19), The reading process of the offset data O from each radiation detection element 7 is performed at the same cycle as the reading process of the main image data D (see FIG. 13).

  Similarly, in the case of the detection method 2, the offset data O is read out by repeating the same processing sequence as the processing sequence before the radiation irradiation start detection (see FIG. 18).

[Regarding a configuration for preventing a step in the true image data D ^* ]
Hereinafter, as shown in FIG. 28, the problem of a step in the true image data D ^*, as well as consider the cause, configuration and the like for preventing occur step in the true image data D ^* Description To do. The operation of the radiographic image capturing apparatus 1 according to this embodiment will also be described.

  In the following, first, a case where the detection method 1 described above is employed as a detection method of radiation irradiation start will be described as an example.

[Configuration 1]
As in the present embodiment described above, the offset data O reading process (see FIG. 19) is configured to be performed repeatedly by the same processing sequence as that before the radiation irradiation start detection (see FIG. 13).

  That is, for example, as shown in FIG. 13, after the completion of the reading process of the main image data D, the same period as the reading process of the leak data dleak and the reset process of each radiation detection element 7 performed before detecting the start of radiation irradiation. Leak data dleak readout processing (see “L” in FIG. 19) and reset processing (see “R” in FIG. 19) of each radiation detection element 7 are alternately performed with τ, and the charge accumulation state (see FIG. 13) and After applying the off voltage from the scanning drive means 15 to each scanning line 5 for the same time, the on-voltage is sequentially applied to each scanning line 5 in the same cycle as the reading process of the image data D, and from each radiation detecting element 7. The offset data O is read out.

[Cause 1-1]
The amount of dark charge read from each radiation detection element 7 is the time during which the TFT 8 connected to the radiation detection element 7 is in the off state, that is, the time Tac in FIG. 13 (hereinafter referred to as the effective accumulation time Tac). It changes according to. At that time, according to the study by the present inventors, it has been found that the relationship between the amount of dark charges read from each radiation detection element 7 and the effective accumulation time Tac is not necessarily linear.

  That is, the amount of dark charge read from each radiation detection element 7 is not necessarily proportional to the effective accumulation time Tac at least in a time region where the effective accumulation time Tac is short. However, if the effective accumulation time Tac is the same time, the amount of dark charge read from each radiation detection element 7 becomes the same amount.

  Therefore, as described above, the reading process of the offset data O is configured to repeatedly perform the same processing sequence as the processing sequence up to the reading process of the main image data D, so that the effective processing in the reading process of the main image data D is performed. The accumulation time Tac (see FIG. 13) and the effective accumulation time Tac (see FIG. 19) in the offset data O reading process are the same time at least for each scanning line 5.

  With the configuration as described above, the amount of dark charge read from each radiation detection element 7 for each scanning line 5 is different between the case of the read processing of the main image data D and the case of the read processing of the offset data O. It will be the same amount.

Therefore, the offset due to the dark charge superimposed on the read main image data D and the read offset data O have the same value for each radiation detection element 7. Therefore, by subtracting the offset data O from the main image data D, the offset due to the dark charge contained in both is canceled out. Therefore, the true image data D ^* calculated by the subtraction process is changed by each irradiation of radiation. The data results only from the charges generated in the radiation detection element 7.

Therefore, it is possible to state that no level difference in the true image data D ^*, it is possible to prevent accurately the level difference occurs in the true image data D ^*.

[Cause 1-2]
Another feature of the above [Configuration 1] is that the leak data dleak alternately with the reset processing of each radiation detection element 7 after the reading processing of the main image data D and before the reading processing of the offset data O. This is in that the reading process is performed.

  As described above, since the radiation image capturing apparatus 1 is not irradiated with radiation during the offset data O readout process, the offset data O readout process includes leak data dleak readout process for detecting the start of radiation irradiation. There is no need to do.

  Therefore, after the reading process of the main image data D and before the reading process of the offset data O, the reading process of the leak data dleak is not performed, and only the reset process of each radiation detection element 7 is performed before the radiation irradiation start detection. Even if it is configured to perform the same period τ as the reset process of each radiation detection element 7 alternately performed with the readout process of the leak data dleak, the main image data is the same as in the case of [Cause 1-1]. The effective accumulation time Tac is the same for each scanning line 5 in the D reading process and the offset data O reading process.

  Therefore, after the reading process of the main image data D and before the reading process of the offset data O, the reading process of the leak data dleak is not performed, and only the reset process of each radiation detection element 7 is performed as described above. It seems to be good.

  Therefore, hereinafter, as in [Configuration 1], after the reading process of the main image data D and before the reading process of the offset data O, the reading circuit 17 (FIG. 6) alternately with the reset process of each radiation detection element 7. The phenomenon and the cause that are the basis for configuring the read processing of the leak data dleak by driving the data will be described.

First, the presupposed phenomenon will be described. In the radiographic imaging device 1 configured as described above, the potential V of each signal line 6 when the reset processing of each radiation detection element 7 is performed is the leak data dleak read processing (in the case of the image data D and d read processing). Is also lower than the potential V of each signal line 6 (that is, the above-described reference potential V ₀ ).

As described above, when the read process is performed, the reference potential V ₀ is applied to each signal line 6 via the operational amplifier 18a (see FIG. 7) of the amplifier circuit 18 of each read circuit 17. _{Even if 0} is changed variously, as described above, the potential V of each signal line 6 at the time of reset processing of each radiation detection element 7 is the same as the potential V of each signal line 6 at the time of read processing of leak data dleak or the like. The phenomenon becomes lower than that. However, the cause of such a phenomenon is not known at present.

When such a phenomenon (a prerequisite phenomenon) occurs, only the reset process of each radiation detection element 7 is performed after the reading process of the main image data D without performing the reading process of the leak data dleak as described above. In this case, as shown in FIG. 20A, the potential V of each signal line 6 starts from a relatively low potential at the time of transition from the reset process (see “R” in the figure) to the charge accumulation state. A state of rising to the reference potential V _{0 is} brought about.

20A and 20B show the case where the reference potential V ₀ is set to [V]. The potential V7a of the first electrode 7a of the radiation detection element 7 in the graph will be described later.

On the other hand, as in [Configuration 1], when the read processing of the leak data dleak and the reset processing of each radiation detection element 7 are alternately performed after the read processing of the main image data D, FIG. As shown in (B), the potential V of each signal line 6 does not decrease as much as when only the reset processing of each radiation detection element 7 is performed from the reference potential V ₀ (see FIG. 20A).

This is because the leak data dleak read process (see “L” in the figure) and reset processing of each radiation detection element 7 (see “R” in the figure) are repeatedly performed in a short time, and therefore the potential of the signal line 6 In other words, the variation in V is flattened, and the potential V of the signal line 6 when only the reset processing of each radiation detection element 7 is performed (the lower potential on the left side of the graph in FIG. 20A) and the readout processing are performed. This is because the value is intermediate between the potential V of the signal line 6 in the charge accumulation state (that is, the reference potential V ₀ ).

  In FIG. 20B, it is described that the potential V of the signal line 6 becomes a constant potential during a period in which the reading process of the leak data dleak and the reset process of each radiation detection element 7 are repeatedly performed in a short time. However, it may move up and down slightly or relatively large.

In the case of FIG. 20B, that is, as in [Configuration 1] above, after the reading process of the main image data D, the reading process of the leak data dleak and the reset process of each radiation detection element 7 are alternately performed. even when configured to perform, when transition to the charge accumulation state, the potential V of each signal line 6 is raised to the reference potential V _0.

  As the potential difference between the potential V of the signal line 6 and the potential V7a of the first electrode 7a of the radiation detection element 7 (see FIG. 6 and FIG. 7) is larger, the potential gradient formed in the TFT 8 becomes steeper, As a result, the amount of charge q leaked from the radiation detection element 7 to the signal line 6 increases. When the charge q leaked from the radiation detection element 7 to the signal line 6 increases, the charge in the radiation detection element 7 decreases accordingly.

20A and 20B, after the transition to the charge accumulation state and the potential V of the signal line 6 becomes the reference potential V ₀ , the potential V of the signal line 6 and the radiation detection element 7 Since the potential difference with the potential V7a of the first electrode 7a is the same, the amount of charge q leaked from the radiation detection element 7 to the signal line 6 through the TFT 8 is the same.

  However, in the state before the transition to the charge accumulation state, the potential of the signal line 6 is higher in the state shown in FIG. 20A than in the state of [Configuration 1] shown in FIG. The potential difference between V and the potential V7a of the first electrode 7a of the radiation detection element 7 becomes relatively small, and the charge q is difficult to leak. Therefore, in the state shown in FIG. 20A, the amount of dark charge remaining in the radiation detection element 7 increases.

  On the other hand, in the state shown in FIG. 20B, the potential difference between the potential V of the signal line 6 and the potential V7a of the first electrode 7a of the radiation detection element 7 is relative to that in the state shown in FIG. And the charge q is likely to leak. Therefore, the amount of dark charge remaining in the radiation detection element 7 is reduced.

  In the case where only the reset processing of each radiation detection element 7 is performed without performing the reading processing of the leak data dleak after the reading processing of the main image data D (see FIG. 20A), as in [Configuration 1] above When the reading process of the leak data dleak and the resetting process of each radiation detection element 7 are alternately performed after the reading process of the main image data D (see FIG. 20B), the difference as described above is caused. Occurs.

Next, a description will be given of the occurrence of a step in the true image data D ^* as shown in FIG. 28 when such a phenomenon occurs.

In the present embodiment, as shown in FIG. 21A, before the reading process of the main image data D, the reading process (L) of the leak data dleak and the resetting process (R) of each radiation detection element 7 are alternately performed. Is called. As described above, the period until the shift to the charge accumulation state, the potential V of the signal line 6 low and shifts to the charge accumulation state, the potential V of the signal line 6 is raised to the reference potential V _0.

  Therefore, the potential difference between the potential V of the signal line 6 and the potential V7a of the first electrode 7a of the radiation detection element 7 is small to some extent until the transition to the charge accumulation state, and leakage from each radiation detection element 7 to the signal line 6 occurs. Although the amount of charge q is small, the potential difference increases after the transition to the charge accumulation state, and the amount of charge q leaking from each radiation detection element 7 to the signal line 6 increases.

  And when it sees about the effective accumulation time Tac for every line L1-Lx of the scanning line 5, the period until it transfers to an electric charge accumulation state differs for each line L1-Lx of the scanning line 5. FIG. That is, the period until transition to the charge accumulation state is the shortest in the detection line L4 of the scanning line 5, and becomes longer in the order of the lines L3, L2,. The longest.

  For this reason, for example, in the detection line L4 of the scanning line 5, the period until the transition to the charge accumulation state is short within the effective accumulation time Tac and the period after the transition to the charge accumulation state is long, so that the detection line L4 is connected to the detection line L4. The amount of charge q leaking from each radiation detecting element 7 to the signal line 6 increases. Therefore, the amount of dark charge remaining in each radiation detection element 7 connected to the detection line L4 is reduced.

  Further, for example, in the readout start line L5 of the scanning line 5, the period until the transition to the charge accumulation state is long within the effective accumulation time Tac and the period after the transition to the charge accumulation state is short, so that the connection is connected to the readout start line L5. The amount of charge q leaking from each radiation detecting element 7 to the signal line 6 is reduced. Therefore, the amount of dark charge remaining in each radiation detection element 7 connected to the readout start line L5 increases.

  Therefore, the amount of dark charge remaining in each radiation detection element 7, that is, the offset amount Od due to dark charge superimposed on the main image data D read out in the reading process of the main image data D is shown in FIG. As shown, the detection line Ln of the scanning line 5 is the smallest and the reading start line Ln + 1 is the largest. In FIGS. 22A and 22B, the detection line of the scanning line 5 is generalized as Ln, and the readout start line is generalized as Ln + 1.

  On the other hand, as described above, after the reading process of the main image data D, only the reset process of each radiation detection element 7 is performed without performing the reading process of the leak data dleak, and the reading process of the offset data O is performed. Even when configured, the same situation occurs as shown in FIG.

  That is, in the detection line L4 of the scanning line 5, since the period until the transition to the charge accumulation state is short within the effective accumulation time Tac, the amount of dark charge remaining in each radiation detection element 7 is reduced. Further, in the readout start line L5 of the scanning line 5, since the period until the transition to the charge accumulation state is long within the effective accumulation time Tac, the amount of dark charge remaining in each radiation detection element 7 increases.

  However, in the case of FIG. 21 (B), the potential difference between the potential V of the signal line 6 and the potential V7a of the first electrode 7a of the radiation detection element 7 during the period up to the transition to the charge accumulation state is as shown in FIG. ) Is relatively smaller than Therefore, almost no charge q leaks from each radiation detection element 7 to the signal line 6.

  Therefore, as shown in FIG. 22B, the read offset data O is the smallest in the detection line Ln of the scanning line 5 as in the case of the offset Od in FIG. 22A, and the read start line Ln. Although it becomes the largest at +1, the width in which the offset data O fluctuates becomes larger than the offset amount Od in FIG.

  That is, roughly speaking, in the state of FIG. 21A, the potential difference between the potential V of the signal line 6 and the potential V7a of the first electrode 7a of the radiation detection element 7 is not so much before and after the transition to the charge accumulation state. Since it does not change, as shown in FIG. 22 (A), the offset Od due to the dark charge superimposed on the main image data D read by the read processing of the main image data D is before and after shifting to the charge accumulation state. It does not fluctuate so much.

  However, in the state of FIG. 21B, the potential difference between the potential V of the signal line 6 and the potential V7a of the first electrode 7a of the radiation detection element 7 changes greatly before and after the transition to the charge accumulation state. The amount of charge q leaking from 7 changes greatly. That is, the amount of dark charge remaining in each radiation detection element 7 varies greatly. For this reason, as shown in FIG. 22B, the read offset data O changes relatively greatly before and after shifting to the charge accumulation state, that is, with the detection line Ln and the read start line Ln + 1 as a boundary. become.

  As described above, after the reading process of the main image data D, only the reset process of each radiation detection element 7 is performed without performing the reading process of the leak data dleak, and the reading process of the offset data O is performed. As shown in FIGS. 22A and 22B, the fluctuation range of the offset Od due to the dark charge superimposed on the main image data D and the fluctuation range of the offset data O read by the offset data O reading process are as follows. It will be in a different state.

Therefore, even if the offset data O is subtracted from the main image data D, as shown in FIG. 23, the offset amount Od due to the dark charge superimposed on the main image data D and the offset data O are not canceled, and the true image It is considered that a step is generated in the data D ^* .

  On the other hand, as in the above [Configuration 1], after the reading process of the main image data D and before the reading process of the offset data O, the reading process of the leak data dleak is performed alternately with the reset process of each radiation detection element 7. With this configuration, the situation up to the reading process of the main image data D is the same as the situation shown in FIG. 21 (A) or 22 (A).

  Further, since the reading process of the leak data dleak is alternately performed after the reset process of each radiation detection element 7 after the reading process of the main image data D, the potential V of the signal line 6 is not shown in FIG. The same situation as (A) is repeated. Therefore, the offset data O to be read fluctuates as shown in the graph of FIG. 22A, not the graph of FIG.

  That is, in the case of the configuration as described in [Configuration 1], both the offset Od due to the dark charge superimposed on the main image data D and the offset data O read out thereafter are shown in FIG. Fluctuate as follows. Therefore, when the offset data O is subtracted from the main image data D, the offset Od due to the dark charge superimposed on the main image data D and the offset data O are accurately offset.

Therefore, the difference Od−O between the offset Od and the offset data O becomes substantially 0 (or a substantially constant predetermined value) in each radiation detection element 7 connected to each line L1 to Lx of the scanning line 5. Therefore, when configured as in [Configuration 1] above, no step is generated in the true image data D ^* .

As described above, when configured as described in [Configuration 1], it is possible to accurately prevent a step in the true image data D ^* .

[Modification in Configuration 1]
Note that the phenomenon that is the premise in [Cause 1-2] described above, that is, the potential V of each signal line 6 when the reset processing of each radiation detection element 7 is performed in the radiographic imaging apparatus 1 is the leak data dleak. When the phenomenon that the potential V is different from the potential V of each signal line 6 at the time of performing the reading process is performed, the phenomenon as shown in FIGS. 20A to 22B occurs. Absent.

  Therefore, under the above [Configuration 1], the leakage data dleak readout processing and the reset processing of each radiation detection element 7 performed after the readout processing of the main image data D and before the readout processing of the offset data O are performed as described above. It is also possible to change to perform only the reset processing of each radiation detection element 7.

  That is, the reset process of each radiation detection element 7 with the same period τ as the reset process of each radiation detection element 7 performed alternately with the readout process of leak data dleak after the reading process of the main image data D and before the start of radiation irradiation detection. I do. Then, after applying the off-voltage to each scanning line 5 from the scanning drive means 15 for the same time as the charge accumulation state before the reading process of the main image data D, each radiation detection element is applied at the same cycle as the reading process of the main image data D The offset data O can be read from 15.

With this configuration, since at least the conditions discussed in [Cause 1-1] in [Configuration 1] are satisfied, it is possible to accurately prevent a step in the true image data D ^*. Become.

[Configuration 2]
Next, as described above, in a normal case, after the reading process of the main image data D (see FIG. 13), before the reading process of the offset data O (see FIG. 19), for example, the reading of the main image data D is performed. In order to remove the remaining portion, it is conceivable to repeat the normal reset process (see FIG. 15) of each radiation detection element 7 without the leak data dleak read process.

However, with this configuration, as described above, the offset Od due to the dark charge superimposed on the main image data D and the offset data O read in the subsequent read processing of the offset data O have the same value. However, as shown in FIG. 28, there may be a problem that a step occurs in the true image data D ^* .

Hereinafter, the cause of such a phenomenon will be considered, and a configuration for preventing a step (see FIG. 28) from occurring in the true image data D ^* will be described.

  In the reset process of each radiation detection element 7 performed alternately with the read process of the leak data dleak before the transition to the charge accumulation state in the read process of the offset data O, as shown in FIG. The reset process of each radiation detection element 7 performed by applying the ON voltage to the lines L5 to Lx and L1 to L4 once is performed once for each scanning line 5 for one surface provided in the detection unit P. This is called reset processing for one frame.

  That is, generally speaking, the line Ln + 1 of the scanning line 5 that is one line above the line Ln + 1 of the scanning line 5 that starts reading in the reading process of the main image data D, that is, the detection start line Ln + 1, that is, the detection. The reset processing of each radiation detection element 7 performed by applying the ON voltage once to each scanning line 5 up to the line Ln is called reset processing for one frame.

  For example, when this reset process is performed by applying an on-voltage twice for each scanning line 5, that is, after sequentially applying an on-voltage from the read start line Ln + 1 to the detection line Ln of the scanning line 5. When the reset process of each radiation detection element 7 is performed by sequentially applying the ON voltage from the read start line Ln + 1 of the scanning line 5 to the detection line Ln again, this is a reset process for two frames.

[Cause 2]
According to the study by the present inventors, the cause of the above problem is that when the reset processing (see FIG. 15) of each radiation detecting element 7 not accompanied by the reading processing of the leak data dleak is performed, the TFT 8 is interposed. This is considered to be because the amount of charge q leaking from each radiation detection element 7 to the signal line 6 changes. This will be specifically described below.

  As described above, the charge q leaks from each radiation detection element 7 through each TFT 8 in the off state and flows into the signal line 6 (see FIG. 10). This is a phenomenon that occurs not only during the reading process of the leak data dleak but also during the reading process of the main image data D and the reading process of the offset data O.

  Therefore, the offset data O read for a certain radiation detection element 7 includes not only the offset Od due to dark charges accumulated in the radiation detection element 7 (see [Configuration 1] above) but also the radiation detection element 7. Also included is an offset due to the total value of the charges q leaked from the other radiation detection elements 7 connected to the signal line 6 connected to each other through the TFTs 8.

  Hereinafter, the total value of the charges q leaked from the other radiation detection elements 7 through the TFTs 8 is simply referred to as the total leakage value Q. Further, the offset amount due to the leak total value Q is referred to as an offset amount Oq.

In addition to the main image data D read out for the radiation detection element 7, in addition to data resulting from the charges generated in the radiation detection element 7 by irradiation of radiation (that is, data corresponding to the true image data D ^* ) The offset includes an offset due to dark charges accumulated in the radiation detection element 7 and an offset Oq due to the leak total value Q.

Ideally, if the offset data O is subtracted from the main image data D, the offset due to the dark charge and the offset due to the leak total value Q included in both are offset, and the radiation is irradiated with the radiation. Only the true image data D ^* resulting from the charge generated in the detection element 7 should remain.

  However, in the studies by the present inventors, if the normal reset process (see FIG. 15) of each radiation detecting element 7 is repeatedly performed after the reading process of the main image data D as described above, it is included in the offset data O. It has been found that the offset Oq due to the leak total value Q may be larger than the offset Oq due to the leak total value Q included in the main image data D.

  More specifically, for example, as shown in FIG. 13, the readout process of the leak data dleak and the reset process of each radiation detection element 7 are alternately repeated, and after the transition to the charge accumulation state, the main image data D When the reading process is performed, the leak total value Q is temporarily read during the reading process of the main image data D.

  That is, for example, the leak data dleak is read during each read operation of the main image data D, and the leak total value Q is read. Then, as shown in FIG. 24, each leak total value Q is obtained for each scanning line 5 including the detection line Ln and the reading start line Ln + 1.

  In the graphs of FIG. 24 and FIG. 25, which will be described later, the horizontal axis is time t, and the ON voltage is applied to each line L1, Ln, Ln + 1, Lx, etc. The applied time is indicated as “L1”, “Ln”, “Ln + 1”, “Lx”, and the like. FIG. 24 shows a case where the total leak value Q is almost the same value for each scanning line 5, but there are cases where the scanning line 5 has a different value depending on the radiation image capturing apparatus 1.

  On the other hand, when the normal reset process (see FIG. 15) of each radiation detection element 7 is repeatedly performed after the reading process of the main image data D, the reset of each radiation detection element 7 is performed immediately thereafter, as shown in FIG. The leak total value Q (that is, the leak data dleak) read in the leak data dleak read processing alternately performed with the processing becomes a very large value.

  Then, it was found that the leak total value Q gradually decreases as the leak data dleak read process and the reset process of each radiation detection element 7 are alternately repeated.

  The influence of the leak total value Q becoming a very large value immediately after the normal reset processing of each radiation detection element 7 may remain until the offset data O reading processing after passing through the charge accumulation state. Then, as shown in FIG. 25, the leak total value Q included in the offset data O is included in the main image data D in the reading start line Ln + 1 of the scanning line 5 and each subsequent scanning line 5. In some cases, the leakage total value Q (see the broken line in the figure, see FIG. 24) is larger.

  Therefore, the difference value Q-Qd obtained by subtracting the leak total value Q included in the offset data O from the leak total value Q included in the main image data D (hereinafter, the latter is referred to as the leak total value Qd) is used as each scanning line. When plotting every five, as shown in FIG. 26, it was found that a step may appear in the difference value Q−Qd between the detection line Ln of the scanning line 5 and the reading start line Ln + 1.

  As described in [Configuration 1] above, the offset Od and the offset data O due to dark charges superimposed on the main image data D are the processing sequence up to the main image data D reading process and the reading of the offset data O. The processing sequence up to the processing is the same processing sequence, and the effective accumulation time Tac for each scanning line 5 is set to the same value in the reading processing of the main image data D and the reading processing of the offset data O. be able to. Therefore, it is canceled out by subtracting the offset data O from the main image data D.

  However, as described above, after the reading process of the main image data D and before the reading process of the offset data O (see FIG. 19), the normal radiation detection elements 7 without the reading process of the leak data dleak are performed. When the reset process (see FIG. 15) is performed, the offset amount Oq based on the total leak value Q included in the main image data D and the offset amount Oq based on the total leak value Qd included in the offset data O are different values as described above. (See FIG. 25), even if they are subtracted, they are not canceled out and a level difference is generated (see FIG. 26).

This is one reason why the offset data O read in the offset data O reading process does not have the same value as the offset superimposed on the main image data D, and there is a step (see FIG. 28) in the true image data D ^* . This is considered to be one of the causes of the

  In order to avoid the occurrence of such a phenomenon, the offset amount Oq based on the leak total value Qd (see FIG. 25) when the offset data O is read out is used when the main image data D is read out. What is necessary is just to comprise so that the offset Oq by the leak total value Q (refer FIG. 24) may become the same value for every scanning line 5. FIG.

  Hereinafter, an example of a configuration for achieving the above object will be described.

[Configuration 2-1]
As one configuration for achieving the above object, for example, after the reading process of the main image data D, the reading process of the leak data dleak is performed before the reading process of the offset data O (see FIG. 19). It is possible to configure not to perform normal reset processing (see FIG. 15) of each radiation detection element 7 that is not present.

  With this configuration, as shown in FIG. 25, the leak total value Q does not become a very large value after the normal reset process of each radiation detection element 7, and the offset data O is read out. The leak total value Qd at this time changes in the same manner as the leak total value Q in the reading process of the main image data D shown in FIG.

  Therefore, for each radiation detection element 7 (or each scanning line 5), the offset Oq based on the leak total value Qd when the offset data O is read is leaked when the main image data D is read. It becomes almost the same value as the offset Oq by the total value Q.

Therefore, by subtracting the offset data O from the main image data D, the offset amount Oq based on the leak total value Q included in the main image data D and the offset amount Oq based on the total leak value Qd included in the offset data O are canceled out. Thus, it is possible to make the true image data D ^* in a state where no step is generated.

  As described above, in the detection method 1 described above, when the readout process of the leak data dleak and the reset process of each radiation detection element 7 are alternately performed (see FIG. 12), the readout of the leak data dleak is performed. Compared with the normal reset processing of each radiation detection element 7 (see FIG. 15), the on-voltage is applied to a certain scanning line 5 until the on-voltage is applied to the next scanning line 5 by the amount of processing. The period τ becomes a long period.

  In the case of such a configuration, it is assumed that, for example, after the read processing of the main image data D, the normal reset processing (see FIG. 15) of each radiation detection element 7 is not performed as described above. Further, it is configured not to perform the reading process of the leak data dleak and the reset process of each radiation detection element 7 as shown in FIG. 19, so that the state immediately shifts to the charge accumulation state after the reading process of the main image data D. Consider the case where

  In this case, in the reading process of the main image data D, the long-cycle reset process is performed as described above, and then the reading process of the main image data D is performed through the charge accumulation state. On the other hand, in the offset data O reading process, after the main image data D, which is performed in a shorter period than the above-described long period reset process, is performed, the offset data O is read out through the charge accumulation state. Become. Therefore, the effective accumulation time Tac described above is different for each scanning line 5 when reading the main image data D and when reading the offset data O.

  Then, as described in [Cause 1-1] above, the offset Od due to the dark charge superimposed on the main image data D and the offset due to the dark charge included in the offset data O have different values. Therefore, even if the offset data O is subtracted from the main image data D, the offset is not canceled out.

  Therefore, in the case of the configuration as described in [Configuration 2-1], as shown in FIG. 19, the leak data dleak is performed after the main image data D read processing and before the offset data O read processing. Read processing and reset processing of each radiation detection element 7 are alternately performed for at least one frame (that is, at least once for each scanning line 5).

  With this configuration, in both the reading process of the main image data D and the reading process of the offset data O, each radiation detection element having a long period is combined with the reading process of the leak data dleak before the charge accumulation state. 7 is performed, and the effective accumulation time Tac described above can be set to the same time for reading the main image data D and for reading the offset data O for each scanning line 5. Become.

[Modification of Configuration 2-1]
Note that the phenomenon that is the premise in [Cause 1-2] described above, that is, the potential V of each signal line 6 when the reset processing of each radiation detection element 7 is performed in the radiographic imaging apparatus 1 is the leak data dleak. If the phenomenon that the potential V is different from the potential V of each signal line 6 at the time of performing the reading process or the like is performed, for the same reason as in [Modification in Configuration 1], [Configuration 1 It is possible to modify the configuration in the same manner as in the case of the modification in

  That is, under the above [Configuration 2-1], instead of alternately performing the reading process of the leak data dleak and the resetting process of the radiation detection elements 7 after the reading process of the main image data D, It is possible to configure so that only the reset process of the radiation detection element 7 is performed.

  Further, in the reading process of the main image data D, the unread portion remains in each radiation detection element 7 as described above. However, in the above [Configuration 2-1], the reading process of the leak data dleak is performed alternately. In the above-described [Modification], most of the unread portions are removed from each radiation detection element 7 by the reset process of each radiation detection element 7.

  Therefore, as described above, even if it is configured not to perform the normal reset process (see FIG. 15) of each radiation detection element 7 without the read process of the leak data dleak, it depends on the unread portion of the main image data D. It has been found that no adverse effects occur.

[Configuration 2-2]
On the other hand, as another configuration for achieving the above-described object, for example, after the reading process of the main image data D, the reading of the leak data dleak is performed before the reading process of the offset data O (see FIG. 19). After performing the normal reset process (see FIG. 15) of each radiation detection element 7 without processing, the readout process of leak data dleak and the reset process of each radiation detection element 7 are performed for a plurality of frames (that is, for each scanning line 5). Multiple times).

  As shown in FIG. 25, when the normal reset processing (see FIG. 15) of each radiation detection element 7 is performed after the reading processing of the main image data D, the leak total value Q becomes a very large value, and thereafter While the reading process of the leak data dleak and the resetting process of each radiation detection element 7 are alternately repeated, the flow gradually decreases.

  Therefore, even if the normal reset process (see FIG. 15) of each radiation detection element 7 is performed after the read process of the main image data D and the leak total value Q becomes a large value, the read process of the leak data dleak and each radiation If the reset process of the detection element 7 is performed for a plurality of frames, the leak total value Qd returns to a state in which the leak total value Qd changes in the same manner as the leak total value Q in the read process of the main image data D shown in FIG.

  Therefore, when configured as in [Configuration 2-2] above, the offset amount based on the leak total value Qd when the offset data O is read out for each radiation detection element 7 (or each scanning line 5). Oq becomes almost the same value as the offset amount Oq by the leak total value Q when the reading process of the main image data D is performed.

Therefore, by subtracting the offset data O from the main image data D, the offset amount Oq based on the leak total value Q included in the main image data D and the offset amount Oq based on the total leak value Qd included in the offset data O are canceled out. Thus, it is possible to make the true image data D ^* in a state where no step is generated.

[Modification of Configuration 2-2]
In addition, in this [Configuration 2-2], when the phenomenon that is the premise in the above [Cause 1-2] does not occur, the above [Modification in Configuration 1] or [Modification in Configuration 2-1] ] For the same reason as in the case of [], it is possible to modify the configuration in the same manner as in [Modification of Configuration 1].

  That is, under the above [Configuration 2-2], instead of alternately performing the readout process of the leak data dleak and the reset process of each radiation detection element 7 after the readout process of the main image data D, It is possible to configure so that only the reset process of the radiation detection element 7 is performed.

[When detection method 2 is used]
Up to this point, the case where the above-described detection method 1 is adopted as the detection method of the start of radiation irradiation has been described. And also as a detection method of the start of radiation irradiation, also when said detection method 2 is employ | adopted, said [configuration 1], [configuration 2-1], [configuration 2-2], or those modifications It is possible to configure exactly the same.

  And although illustration is abbreviate | omitted, in the read-out process of offset data O, it is comprised so that the same process sequence as the process sequence (refer FIG. 18) before the irradiation start detection may be performed repeatedly.

  That is, for example, after the reading process of the main image data D is completed as shown in FIG. 18, the image is read at the same period τ as the reading process of the image data d for irradiation start detection performed before the detection of radiation irradiation start. Data d is read out, an off voltage is applied from the scanning drive means 15 to each scanning line 5 for the same time as the charge accumulation state (see FIG. 18), and then each radiation is emitted in the same cycle as the read processing of the main image data D. A process for reading the offset data O from the detection element 7 is performed.

  In addition, the phenomenon that is the premise of the above [Cause 1-2], that is, the potential V of each signal line 6 when the reset processing of each radiation detection element 7 is performed in the radiation imaging apparatus 1 is the image data D. In the case where the phenomenon that the potential V is different from the potential V of each signal line 6 when the reading process of d is performed does not occur, the reading process of the image data d is performed instead of the reading process of the main image data D. In addition, it is possible to perform a reset process for each radiation detection element 7 with the same period τ.

With the configuration described above, even when the above-described detection method 2 is adopted as a method for detecting the start of radiation irradiation, it is possible to accurately prevent a step from occurring in the true image data D ^* .

  As described above, according to the radiographic image capturing apparatus 1 according to the present embodiment, the detection method 1 and the detection method 2 described above are employed, and before the radiographic image is captured, leak data dleak and image data for detecting the start of irradiation are obtained. Since d is read and the start of radiation irradiation is detected based on it, it is possible to accurately detect that the radiation image capturing apparatus 1 itself has irradiated the radiation.

  Further, the offset amount Od due to the dark charge contained in the main image data D and the offset amount Oq due to the leak total value Q, and the offset amount Od due to the dark charge contained in the offset data O and the offset amount Oq due to the leak total value Q Can be set to the same value for each radiation detection element 7.

  Therefore, by subtracting the offset data O from the main image data D, the offset amount Od due to the dark charge and the offset amount Oq due to the leak total value Q can be accurately canceled and superimposed on the main image data D. The offset amount being offset and the offset data O are accurately offset.

Therefore, by subtracting the offset data O from the main image data D, it is possible to accurately prevent a step (see FIG. 28) from occurring in the true image data D ^* calculated for each radiation detection element 7. Become. And when using the radiographic image image | photographed with the radiographic imaging apparatus 1 for the medical diagnosis etc., a streak appears in a radiographic image, or a streak and a lesion part of a patient overlap on a radiographic image, and a lesion part It is possible to accurately prevent problems such as oversight.

  Needless to say, the present invention is not limited to the above-described embodiment, and can be changed as appropriate.

DESCRIPTION OF SYMBOLS 1 Radiographic imaging device 5 Scanning line 6 Signal line 7 Radiation detection element 8 TFT (switch means)
15 Scanning drive means 17 Reading circuit 22 Control means D Image data d as main image Image data for detection of irradiation start leak data leak_th threshold dth threshold O offset data P detector q charge r small region τ period

Claims (10)

A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other, and a plurality of radiation detection elements arranged in a two-dimensional manner in each small region partitioned by the plurality of scanning lines and the plurality of signal lines A detection unit comprising:
Scan driving means for applying an on voltage or an off voltage to each of the scanning lines;
Switch means connected to each of the scanning lines and causing the signal lines to discharge charges accumulated in the radiation detection element when an on-voltage is applied;
A readout circuit that converts the electric charge emitted from the radiation detection element into image data and reads the image data;
Control means for controlling at least the scanning drive means and the readout circuit to perform readout processing of the image data from the radiation detection element;
With
The control means includes
The charge leaked from each radiation detection element via each switch means in a state where an off voltage is applied to each scan line from the scan driving means to turn off each switch means before radiographic image capturing. Alternately performing leak data read processing for converting the data into leak data and reset processing of the radiation detection elements performed by sequentially applying an ON voltage to the scan lines from the scan driving unit,
When it is detected that radiation irradiation has started when the read leak data exceeds a threshold value, an off voltage is applied to each scanning line from the scanning drive means to generate charges generated by radiation irradiation. After shifting to a charge accumulation state to be accumulated in the radiation detection element, the image data is read from each radiation detection element, and
After the image data read processing, the leak data read processing and the radiation detection element of each of the radiation detection elements are performed in the same cycle as the leak data read processing and the reset processing of each radiation detection element performed before the start of radiation irradiation detection. The reset process is alternately performed, and after applying an off voltage to the scan lines from the scan driving unit for the same time as the charge accumulation state, the radiation detection elements are applied at the same cycle as the image data read process. A radiographic imaging apparatus characterized by causing the offset data to be read out.   Each of the radiation detection elements that is alternately performed with the leak data reading process without performing the reset process of each radiation detection element without the leak data reading process after the image data reading process. 2. The radiation according to claim 1, wherein the reset process is performed at least once for each scanning line, and the readout process of the leak data and the reset process of the radiation detection elements are alternately performed. Image shooting device.   The control means performs reset processing of the radiation detection elements not accompanied by the leak data read processing after the image data read processing, and then alternately performs the radiation data read processing. The radiographic image according to claim 1, wherein the reset process is performed a plurality of times for each scanning line, and the readout process of the leak data and the reset process of the radiation detection elements are alternately performed. Shooting device. The control means, after the read processing of the image data,
The leak data read process and the reset process of each radiation detection element are alternately performed at the same cycle as the leak data read process and the reset process of each radiation detection element performed before the start of radiation irradiation detection. instead of,
Same as the reset process of each radiation detection element performed alternately with the readout process of the leak data before detecting the start of radiation irradiation without performing the reset process of each radiation detection element without the readout process of the leak data. The radiographic image capturing apparatus according to claim 1, wherein only the reset process of each radiation detection element is performed at least once for each scanning line in a cycle. The control means, after the read processing of the image data,
The leak data read process and the reset process of each radiation detection element are alternately performed at the same cycle as the leak data read process and the reset process of each radiation detection element performed before the start of radiation irradiation detection. instead of,
Same as the reset processing of each radiation detection element that is performed alternately with the readout processing of the leak data after performing the reset processing of each radiation detection element without the readout processing of the leak data and before detecting the start of radiation irradiation The radiographic image capturing apparatus according to claim 1, wherein only the reset process of each radiation detection element is performed a plurality of times for each scanning line in a cycle. A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other, and a plurality of radiation detection elements arranged in a two-dimensional manner in each small region partitioned by the plurality of scanning lines and the plurality of signal lines A detection unit comprising:
Scan driving means for applying an on voltage or an off voltage to each of the scanning lines;
Switch means connected to each of the scanning lines and causing the signal lines to discharge charges accumulated in the radiation detection element when an on-voltage is applied;
A readout circuit that converts the electric charge emitted from the radiation detection element into image data and reads the image data;
Control means for controlling at least the scanning drive means and the readout circuit to perform readout processing of the image data from the radiation detection element;
With
The control means includes
Prior to radiographic image capturing, an on voltage is sequentially applied to each scanning line from the scanning driving means to perform a reading process of the image data for detection of irradiation start,
When it is detected that radiation irradiation has started when the read image data exceeds a threshold value, an off voltage is applied to each scanning line from the scanning drive means to generate charges generated by radiation irradiation. After shifting to a charge accumulation state to be accumulated in the radiation detection element, the image data as a main image from each radiation detection element is read out, and
After the reading process of the image data as the main image, the reading process of the image data for detecting the start of irradiation is performed at the same cycle as the reading process of the image data for detecting the start of irradiation performed before detecting the start of irradiation of radiation. In addition, after applying an off voltage to the scanning lines from the scanning driving means for the same time as the charge accumulation state, the offset data from the radiation detection elements is in the same cycle as the read processing of the image data as the main image. The radiographic imaging device characterized by performing the read-out process.   The control means reads the image data for detecting the start of irradiation performed before detecting the start of radiation irradiation without performing the reset process of each radiation detection element after the process of reading the image data as the main image. The radiographic image capturing apparatus according to claim 6, wherein reading processing of the image data for detecting the start of irradiation is performed at least once for each scanning line at the same cycle as the processing.   The control means reads out the image data for detecting the start of irradiation after performing the reset processing of each radiation detection element after the read processing of the image data as the main image and before detecting the start of radiation irradiation. The radiographic image capturing apparatus according to claim 6, wherein a reading process of the image data for detecting the start of irradiation is performed a plurality of times for each scanning line at the same cycle as the process. The control means, after the read processing of the image data as the main image,
Instead of letting the image data for reading start detection be read out in the same cycle as the process for reading out image data for detecting the start of irradiation performed before detecting the start of irradiation of radiation,
The reset processing of each radiation detection element is performed at least once for each scanning line in the same cycle as the reading processing of the image data for detection of irradiation start performed before the start of radiation irradiation detection. Item 7. The radiographic image capturing device according to Item 6. The control means, after the read processing of the image data as the main image,
Instead of letting the image data for reading start detection be read out in the same cycle as the process for reading out image data for detecting the start of irradiation performed before detecting the start of irradiation of radiation,
After the reset process of each radiation detection element, the reset process of each radiation detection element is further performed in the same cycle as the reading process of the image data for detection of irradiation start performed before the start of radiation irradiation detection. The radiographic image capturing apparatus according to claim 6, wherein the scanning is performed a plurality of times for each scanning line.

Images